Boot-strap type driver circuit for producing high voltage pulses



April 19, 1960 p, BAUM 2,933,690

BOOT-STRAP TYPE DRIVER CIRCUIT FOR PRODUCING HIGH VOLTAGE PULSES Filed March 20, 1957 900 Vol 75 POWE SUPPZY F ij -1 TT Z INVENTOR.

United rates Patent BOOT-STRAP TYPE DRIVER CIRCUIT FOR PRO- DUCING HIGH VOLTAGE PULSES Peter A. Baum, Manhasset, N.Y., assignor to the United States of America as represented by the Secretary of the Air Force Application March 20, 1957, Serial No. 647,462

1 Claim. (Cl. 328-176) This invention relates to a boot-strap type driver circuit for producing high-voltage pulses to be fed to a transmitter.

An object of the invention is to eliminate the need for a transformer for producing the high voltage pulses and thereby eliminate the damping and recovery troubles that would ordinarily result from the use of such a transformer.

Another object is to provide a boot-strap type driver circuit which permits the use of a lower drive voltage than in prior art devices and still maintain a large current through the tube as the cathode potential rises.

These and other objects will be understood more clearly with reference to the following detailed description or the invention.

In the drawing,

Fig. 1 is a circuit schematic of the boot-strap type driver circuit of the invention.

Fig. 2 is a circuit schematic of the heater supply circuit for the screen grid tube of Fig. 1.

Referring more particularly to Fig. 1, reference numeral 10 refers to a twin tetrode vacuum tube having a pair of anodes ii, a pair of cathodes 12, a pair of screen grids 13, and a pair of grids 14. Since the dual electrode system is for the purpose of increasing the current capacity or the tube, these elements will be referred to in this disciosure as if they were single electrodes. The anode 11 is connected directly to a plus 1800 volt supply 19 and the screen grid 13 is connected to a plus 900 volt supply 2! through a resistance element R A voltage divider made up of resistance elements R R R and R is connected between the screen grid and ground. Cathode 12 is connected to the voltage divider at a point between resistance elements R2 and R A condenser C is connected between the screen grid and cathode so that the screen grid will experience a rise in potential when the cathode potential rises as the tube is fired. Resistor R is shunted by a voltage regulator tube 15, which maintains the grid to cathode bias on tube constant regardless of the duty cycle. A transformer T is com nected between the grid and cathode of tube 10 and supplies a driving pulse between the grid and cathode through a by-pass condenser C In Fig. 2, heater elements 16 are the heater elements for tube 10. The heater voltage is applied to the heaters 16 through an isolating transformer T to prevent the heater-cathode peak voltage from being exceeded.

In the operation of the device of Fig. 1, condenser C is charged through R between the appearance of pulses at T By the proper choice of circuit constants, a large portion of the 900 volt screen supply voltage can be made to appear across the condenser C When a pulse is applied at T thereby causing tube 16 to conduct, the current through R;,, R and R causes the cathode potential to rise. Due to the charge on C screen grid 13 experiences a corresponding rise in potential, thereby maintaining the screen grid to cathode voltage substantially constant. Voltage regulator tube 15 maintains the control grid to cathode bias voltage across resistor R substantially constant regardless of'the duty cycle. By the proper choice of circuit elements the total voltage from anode to ground can be made to split during conduction of tube 10 so that approximately 200 volts will appear between the anode 11 and a tap 17 on the voltage divider and the remaining 1600 volts will appear between tap 17 and ground. To get a 600 volt pulse output, tap 18 is connected to a lower point on the voltage divider.

There is thus provided a boot-strap type driver circuit for producing high-voltage pulses without the use of a step-up transformer.

While a specific embodiment of the invention has been described in some detail, it will be understood that numerous changes may be made without departing from the general principles and scope of the invention.

I claim:

A device for producing high voltage pulses comprising: a screen grid tube, a high voltage supply connected to the anode of said tube, an intermediate voltage supply connected to the screen grid of said tube, a voltage divider connected between the screen grid and ground, means for connecting the cathode of said tube to a point on said voltage divider, means connected between the control grid of said tube and a second point on said voltage divider for applying a pulse signal between said grid and the cathode, means connected across said two points for maintaining a constant grid to cathode bias on said tube, means connected between said cathode and said screen grid for causing the screen grid to rise in potential when the cathode potential rises, and output means connected to a plurality of points on said voltage divider.

References Cited in the file of this patent, UNITED STATES PATENTS 2,357,405 Katzin Sept. 5, 1944 2,435,331 Street Feb. 3, 1948 2,685,619 Orlando Aug. 3, 1954 2,770,686 Hallden Nov. 13, 1956 2,782,867 Hall Feb. 26, 1957 FOREIGN PATENTS 146,789 Australia June 11, 1952 OTHER REFERENCES Principles of Radar, published 1946 by McGraw-Hill Book Co. Inc., pages 6-53, 6-54. 

